Dynamic spectrum management level-3 (DSM3) or “vectoring” is a technique in DSL communication systems for mitigating the crosstalk inherent in twisted-pair networks by cancelling and/or precoding signals from a multiplicity of collocated transceivers. The G. vector standard (G.993.5) provides a framework for actively cancelling far-end crosstalk (FEXT) among lines in the vectored DSL system. Certain aspects of vectoring that can be considered background art are described in U.S. Patent Publ. No. 2009/0245340, U.S. Patent Publ. 2008/0049855, U.S. Patent Publ. No. 2010/0195478, U.S. Patent Publ. No. 2009/0271550, U.S. Patent Publ. No. 2009/0310502, U.S. Patent Publ. No. 2010/0046684 and U.S. Pat. No. 7,843,949.
In vectored VDSL2, backchannel information may be communicated from the VTU-R (i.e., the customer-end or remote device) to the VTU-O (i.e., the central office device) during Showtime either via embedded operations channel (EOC) encapsulation or via Layer 2 encapsulation. The VTU-R supports both encapsulation methods and the VCE selects its preferred communication method during initialization. In either case, a VTU-R transports the backchannel information to the VTU-O across its corresponding wire-pair at which point the backchannel information is routed to the VCE by implementation specific means within the access node.